please help i don’t understand

[tex]y = \frac{bfm}{km -f}\\[/tex]
Solving [tex]ky -bf = \frac{fy}{m}\\[/tex] for [tex]y[/tex]:
[tex]ky -bf = \frac{fy}{m} \\ (ky -bf) \cdot m = \frac{fy}{m} \cdot m \\ kym -bfm = fy \\ kym -bfm +bfm = fy +bfm \\ kym = fy +bfm \\ kym -fy = fy +bfm -fy \\ kym -fy = bfm \\ y(km -f) = bfm \\ \frac{y(km -f)}{km -f} = \frac{bfm}{km -f} \\ y = \frac{bfm}{km -f}[/tex]